<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    <div :class="cls1">
      div1
    </div>
    <div :class="['box2', cls1]">
      div2
    </div>
    <div :class="{active: 1===1, b:isB, c: false}">
      div3
    </div>
    <div :class="['box2', cls1,{active: 1===1, b:isB, c: false}]">
      div4
    </div>
  </div>
  <script src="./vue.global.js"></script>
  <script>
    const { createApp } = Vue;
    const app = createApp({
      data(){
        return {
          cls1: 'box',
          isB: true
        }
      }
    })
    app.mount('#app')
  </script>
</body>
</html>